OAKLAND — In the most horrific day in Oakland Police Department history, a parolee shot to death three police sergeants within two hours of one another Saturday afternoon.

When officers tracked down the suspect, a fourth officer was shot and was in critical condition Saturday night.

The three veteran officers killed were sergeants: Mark Dunakin, 40, of Tracy, a traffic officer with the department since 1991; Erv Romans, 43, of Danville, a 13-year veteran with the force; and Dan Sakai, 35, a nine-year veteran, police said.

Romans and Sakai were SWAT team members. It was the first time any sergeant in the department had been slain.

Officer John Hege, 41, of Concord, was on life support at Highland Hospital. A bullet grazed a fifth, unidentified officer. He was treated and released from the hospital.

The suspect was identified as Oakland resident Lovelle Mixon, 26. He was on parole for assault with a deadly weapon, police said. He had a no-bail warrant for his arrest on charges of violating parole. He had previous convictions in Alameda County for grand theft and possession of marijuana.

“I wouldn’t wish this on any of my colleagues in the United States,” said acting police Chief Howard Jordan during a news conference Saturday night. “This is very daunting for us, but we are very resilient. We are a big family and we rely on each other for support.”

The first shooting happened in the 7400 block of MacArthur Boulevard about 1:16 p.m. when Dunakin and Hege were shot with a handgun during a traffic stop. What led to the shooting was not known.

A man, who did not want be identified, said he heard gunshots and saw the officers lying on the road.

“I went over to one officer and saw he was bleeding from his helmet pretty bad,” he said. “The other officer was lying motionless.”

He said the officer lying near a car was shot twice in the face. One bullet was lodged in his jaw and the other in his neck. The man said he performed CPR until other officers arrived.

Helicopters hovered for hours over the crime scene.

Dozens of Oakland police, Highway Patrol officers and Alameda County sheriff’s deputies cordoned off stretches of blocks around 73rd and 74th avenues and MacArthur Boulevard.

Then they heard that the suspect was in an apartment around the corner on 74th Avenue.

Police surrounded the building and, after the Oakland SWAT team tried to communicate with the suspect, they entered the building.

Mixon opened fire with an assault weapon, police said.

Sakai and Romans were fatally wounded and another officer was grazed in the head. Other officers killed Mixon. No other occupants in the complex were injured.

As the evening wore on, city leaders held a news conference at the Police Department.

Joining Oakland Mayor Ron Dellums there were council members Larry Reid, Desley Brooks and state Attorney General Jerry Brown.

Dellums said there are no words to express “the shock, grief, sadness and sorrow we feel.

“Our hearts go out to the families, whose level of tragedy and loss is beyond any comprehension.”

Never before had so many police officers been killed in the line duty on the same day in Oakland.

In honor of the officers, state Capitol flags will be flown at half-staff today, Gov. Arnold Schwarzenegger said.

As news of the shootings reached the Oakland police community, officers showed up in droves at both Highland Hospital, where the officers were taken, and at the Eastmont Substation, a few blocks from the shooting scene.

“This is just unbelievable; everyone is in shock,” said an Oakland police sergeant.

A neighbor of Hege’s in Concord said the officer was single and had no children.

“He didn’t deserve what he got, that’s for sure,” said the neighbor, who gave only his first name, Peter.

He said the two were good friends, eating breakfast together almost every Sunday. Sometimes they talked about the risks of the job.

Three police officers were outside Dunakin’s home in Tracy on Saturday night — including one apparently from the San Francisco Police Department.

The tidy two-story home is in the Red Bridge Housing Development, one of the city’s more affluent subdivisions. It appeared that relatives and friends were entering and leaving the house. When approached, an officer requested that the family be left alone.

Dunakin was married and had three children.

The last time an officer was killed and another was shot on the same day in Oakland was in 1974 during a gang-involved robbery.

The last time an Oakland officer was killed was in 2004 when William Seuis, 39, died in a hit-and-run crash.

David Guider and Wendell Troyer were the last two officers to die on the same day in the line of duty, in a helicopter crash in 1974.

Before Saturday, 47 Oakland police officers had been killed in the line of duty since the department was formed in 1867.

Saturday’s slaying were the first time since 1970 that four law-enforcement officers perished at one time in California.

That year, four Highway Patrol officers were killed in a shootout on a Newhall freeway offramp.

Harry Harris is a breaking news reporter for the Bay Area News Group. He began his Oakland Tribune career in September 1965 as a 17-year-old copyboy. He became a reporter in 1972 and is considered one of the best crime and breaking news reporters in the country. He has covered more than 4,800 murders in Oakland alone as well as tens of thousands of other crimes. He has also mentored dozens of young reporters, some of whom continue to work in journalism today.

In a video clip recorded by a student, a psychology instructor at Orange Coast College told her class that the election of Donald Trump was “an act of terrorism” – prompting an official complaint from the school’s Republican Club.

Homegrown tech entrepeneurs and educators from West Contra Costa County participate in an Hour of Code event Wednesday at the Richmond Police Activities League aimed at getting more African-Americans, Latinos and minorities into the tech field, as part of Computer Science Education Week, from Dec. 5 to 11.